Gas blast circuit breaker for high voltages

ABSTRACT

A gas blast circuit breaker for high voltages has an elongated breaking chamber permanently filled with compressed gas which contains a power break with a movable contact. An operating device for the movable contact is positioned at one end of the breaking chamber. An exhaust channel runs through the breaking chamber with its outlet at the other end of the breaking chamber. A blast valve is mounted for closing and opening the outlet. The blast valve is actuated towards closing position by fluid under pressure from the breaking chamber, supplied through a passage leading by a first auxiliary valve. The blast valve is closed by the opening movement of the movable contact through a push rod which acts to open the first auxiliary valve when the contact opens. A second auxiliary valve connected to the outside and also operated by the push rod is opened when the breaker is closed so as to open the blast valve.

United States Patent [191 Sandkvist et al.

[ GAS BLAST CIRCUIT BREAKER FOR HIGH VOLTAGES [75] Inventors: Hugo Sandkvist; Tore Nygaard,

both of Ludvika, Sweden [73] Assignee: Allmanna Svenska Elektriska Aktiebolaget, Vasteras, Sweden 22 Filed: Dec. 27, 1972 [21] Appl. No.1 318,907

[30] Foreign Application Priority Data Dec. 3], 1971 Sweden l700l/7l [56] References Cited UNITED STATES PATENTS Carter et al 200/148 R Apr. 16, 1974 Primary Examiner-Robert S. Macon [5 7] ABSTRACT A gas blast circuit breaker for high voltages has an elongated breaking chamber permanently filled with compressed gas which contains a power break with a movable contact. An operating device forthe movable contact is positioned at one end of the breaking chamber. An exhaust channel runs through the breaking chamber with its outlet at the other end of the breaking chamber. A blast valve is mounted for closing and opening the outlet. The blast valve is actuated towards closing position by fluid under pressure from the breaking chamber, supplied through a passage leading by a first auxiliary .valve. The blast valve is closed by the opening movement of the movable contact through a push rod which acts to open the first auxiliary valve when the contact opens. A second auxiliary valve connected to the outside and also operated by the push rod is opened when the breaker is closed so as to open the blast valve.

8 Claims, 3 Drawing Figures ATENTEUAPR 16 I974 380E001 SHEET 3 UF 3 Fig.

GAS BLAST CIRCUIT BREAKER FOR HIGH VOLTAGES BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas blast circuit breaker for relatively high voltages (of the order of 1,000 kV). The breaker is preferably of the kind having breaking elements with so-called double blasting, which means that compressed gas is blown towards the two base points of the arc during breaking.

2. The Prior Art Such a breaking element generally consists of a breaking chamber which is permanently pressurized during operation. Said breaking chamber contains a power break and is provided with a blast valve at each end. As a rule, the breaking chamber is attached by one end to a central insulator pillar. At this end is an operating device for the movable contact which, along with the blast valve arranged at the attachment end, receives its operating impulses from the central operating system. The blast valve at the external, free end of the element is generally operated through a separate compressed-air conduit or with the help of the pressure drop occurring when the blast valve at the attachment end of the element is opened. These systems of operation for the external blast valve are, however, relatively slow, and therefore they are less suitable for breakers for ultra-high voltages.

Summary of the Invention The purpose of the present invention is to achieve a relatively simple and quick-working means in a breaking element with double blasting for transmitting an operating impulse from the attachment end of the breaking element, where there is a central operating system, to the free end of the element, where the impulse in the present case is to be used for operation of a blast valve. In thiscase the impulse is to be transmitted past the breaking gap of the breaking element, said breaking gap being short-circuited when the breaker is closed, and open and subject to voltage when the breaker is open. This problem is solved according to the invention by providing operating means for the blast valve which includes a space connectable either to the pressurized chamber-or to the pressure in which the blast valve is exposed, valves for connecting this space either to the outside or to the pressurized section, and a push rod means which is controlled by the movement of the movable contact and which connects this space to the outside when the movable contact moves to closed position to allow opening for the blast valve and to the pressurized space to close the blast valve when the movable contact moves away from closed position.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be further described with reference to the accompanying drawing, in which FIGS. 1, 2 and 3 show in cross-section three different embodiments of control devices for the external blast valve in a breaking element with double blasting.

DESCRIPTION OF THE PREFERRED EMBODIMENTS All the constructions shown in the drawing refer to breaking elements having an elongated breaking chamber l of insulating material which contains a power break, the movable contact 2 of which is tubular and cooperates with a central sealing piston 3. In all three figures the respective breaking element is shown in closed position, the movable contact 2 lying pressed against the sealing piston 3 and separating an outer space 4, which is permanently pressurized during operation, from an inner space 5 which is under atmospheric pressure in this position of the breaker. The space 5 constitutes an exhaust channel running axially through the breaking element, said exhaust channel being closed by means of blast valves, of which there is one at each end of the breaking element. The internal blast valve (at the attachment end of the breaking element) is not shown in the drawing. When the breaker is closed the blast valves are open, and space 5 is under atmospheric pressure, and when the breaker is open the blast valves are closed, space 5 being pressurized.

When the expressions opening, closing and open and closed position are used in the following, these always refer to the motion or position of the main contact 2.

In the device according to FIG. 1, the external blast valve consists of a tubular valve member 6 which is axially displaceable towards and from a sealing ring 7 for closing and opening an outlet channel 8, through which the space 5 communicates with the open air. The valve member 6 is urged in the closing direction by a spring 9, by which the blast valve is closed when the breaker is under'no pressure. The right end of the valve member 6 is formed as a piston, which on its left-hand side defines a space 10 and on its right-hand side a space I l. The space 10 is pressurized since it is permanently connected to the outer space 4 of the breaking chamber through a channel 12, said outer space 4 being permanently pressurized during operation. Space 11 can be pressurized through an inlet channel 13 with an inlet valve 14 and relieved of pressure through a discharge channel 15 with a discharge valve 16. The valves 14 and 16 are operated by a push-rod 17, which is pressed into contact with the sealing piston 3 by a return spring 18. In order to operate the valve 14, this valve is also provided with a spindle l9 directed perpendicularly to the push-rod. In the'open position of the blast valve its operating piston, which is provided with a sealing ring 20 with the diameter d,, is pressed against a valve seat which cooperates with said sealing ring. A sealing ring 21 with the inner diameter d, seals against the outer cylinder surface of the blast valve member 6. The diameter of the blast valve sealing ring 7 is designated d;,. The construction shown in FIG. 1 operates in the following way:

When the movable contact 2 hits the sealing piston 3 at the end of the closing movement, the motion is transferred to the push-rod 17. The spindle 19 on the valve 14 which, when the breaker is open, has been held open by a thicker part 22 on the push-rod with the diameter d, follows the conical surface 23 of the pushrod towards its smaller diameter'and the valve 14 -closes. The push-rod 17 also hits discharge valve 16 which is closed when the breaker is open, and opens it.

respectively. The outlet channel 8 is now uncovered and the space 5 is discharged.

When the breaker is to be opened, the contact 2 leaves the sealing piston 3. Valve piston 16 and pushrod 17 are brought back by the spring 18. Valve piston 16 closes the discharge channel 15 from space 11, and valve 14, the spindle 19 of which moves up on the thicker part 22 of the push-rod, opens the entrance channel 13 to space 11. Blast gas then flows between the movable contact and the fixed contact. When the pressure has increased sufficiently in the space 11, the piston 6 moves towards the sealing ring 7 and closes the outlet channel 8. The piston 6 is now kept in this position by the pressure on the annular surface A A where A, and A designate circular surfaces with the diameter d, and d respectively. By suitably dimensioning the through-flow area of the entrance valve 14 and the channel 13, the desired time between contact separation and closing of the blast valve is obtained, the socalled blowing time.

FIG. 2 shows an embodiment with the entrance valve 14 positioned in line with the discharge valve 16. A spring 24 keeps the valve 14 closed in the closed position of the breaker. This spring is dimensioned in such a way that it seals in the position shown, but in the open position of the breaker, when the discharge valve 16 is pressed against its sealing edge, the spring 24 is unloaded so much that the entrance channel 13 is uncovered.

The embodiment shown in FIG. 3 differs from that shown in FIG. 1 in that the entrance valve 14 and the channel 13 are replaced by a relatively narrow channel 25 to pressurize the space 11 (when the blast valve is to be closed) from a space 26 which becomes pressurized when the contact 2 leaves the sealing piston 3 during opening of the breaker. In addition, in the arrangement according to FIG. 3, the push-rod is not provided with the thicker part 22 shown in FIG. 1 since it need only operate the discharge valve 16.

The device according to FIG. 3 operates as follows: When the movable contact 2 hits the sealing piston 3 at the end of the closing movement, the motion is transferred'to the push-rod 17. The push-rod 17 opens the discharge valve 16, which is closed when the breaker is open. The space 11 is evacuated through channel 15 and the pressure in space on the other side of piston 6 acts on the piston to press it against the sealing edge with the diameter d, and to keep it in this position by the pressure on the annular surface A, A The outlet channel 8 is now uncovered and the space 5 is relieved of pressure. Space 26 is discharged at the same time as space 5.

When opening the breaker, the contact 2 leaves the sealing piston 3. Valve piston 16 and push-rod 17 are returned by the spring 18. Valve piston 16 closes the discharge channel from space 11. When the contact 2 leaves the sealing piston 3, space 26 is also pressurized, and from space 26 the pressure is transmitted to space 11 through channel 25. When the pressure has increased sufficiently in this space, piston 6 moves towards the sealing ring 7 and closes the outlet channel 8. The piston 6 is now kept in this position by the pressure on the annular surface A A By suitably dimensioning channel 25, the desired time between contact separation and closing of the blast valve is obtained, the so-called blowing time.

The constructions shown in the drawing show only one single push-rod 17. The invention is however not limited to this embodiment but includes also embodiments with more push-rods, each one operating a dis- 5 charge valve 16. In the embodiments according to FIGS. 1 and 2, more entrance valves 14 can be used. However, these need not be the same in number as the discharge valves. Such an entrance valve does not necessarily have to be operated from the same push-rod as a discharge valve, but can be operated by a special push-rod. Further, the contact 2 need not act on the push-rods through the sealing-piston 3 or any other intermediate part, but this action may occur directly between the contact and the push-rods.

We claim:

1. Gas blast circuit breaker for high voltages with an elongated breaking chamber (1) permanently filled with compressed gas and containing a power break having a first contact and a second movable contact (2) movable towards and away from the first contact, an exhaust channel (5) running axially through the chamber (1) to the end thereof remote from the movable contact (2), a blast valve (6), movable to open and close said exhaust channel (5), said blast valve being isolated from said movable contact in the open position of the breaker, means (9, 10, 11) for moving said blast valve (6) between opening and closing positions, and control means for said moving means including means engageable by said movable contact and operable as the movable contact moves from closed position to produce closing of said blast'valve and as the movable contact returns to closed position to produce opening of the blast valve, control means including push-rod means extending and movable in the same direction as the movable contact.

2. Gas blast circuit breaker according to claim 1, in which the movable contact (2) constitutes the movable valve member of a central blast valve (2,3) positioned in the immediate vicinity of the power break.

3. Gas blast circuit breaker according to claim 2, in which the central blast valve includes a movable sealing piston (3) interposed between the movable contact and the push-rod means.

4. Gas blast circuit breaker according to claim 2, having a first operating space (11) for the blast valve, a second space (26) close to the sealing piston (3), a channel (25) connecting said first and second spaces, said control means including means for discharging said spaces when the movable contact is in the closed position and pressurizing said spaces when the movable contact (2) leaves the sealing piston (3) during opening of the circuit breaker.

5. Gas blast circuit breaker according to claim 1, in which the blast valve moving means includes an operating space (11) for the movable valve member (6) of the external blast valve, and the control means includes valve means (16) operatively connected to the pushrod means to discharge said operating space.

6. Gas blast circuit breaker according to claim 5, including an inlet valve (14) for said operating space (1 1) for admitting pressure gas thereinto, said push-rod means including means to open said inlet valve when the movable contact moves away from closed position.

6o 7. Gas blast circuit breaker according to claim 6, in 

1. Gas blast circuit breaker for high voltages with an elongated breaking chamber (1) permanently filled with compressed gas and containing a power break having a first contact and a second movable contact (2) movable towards and away from the first contact, an exhaust channel (5) running axially through the chamber (1) to the end thereof remote from the movable contact (2), a blast valve (6), movable to open and close said exhaust channel (5), said blast valve being isolated from said movable contact in the open position of the breaker, means (9, 10, 11) for moving said blast valve (6) between opening and closing positions, and control means for said moving means including means engageable by said movable contact and operable as the movable contact moves from closed position to produce closing of said blast valve and as the movable contact returns to closed position to produce opening of the blast valve, control means including push-rod means extending and movable in the same direction as the movable contact.
 2. Gas blast circuit breaker according to claim 1, in which the movable contact (2) constitutes the movable valve member of a central blast valve (2,3) positioned in the immediate vicinity of the power break.
 3. Gas blast circuit breaker according to claim 2, in which the central blast valve includes a movable sealing piston (3) interposed between the movable contact and the push-rod means.
 4. Gas blast circuit breaker according to claim 2, having a first operating space (11) for the blast valve, a second space (26) close to the sealing piston (3), a channel (25) connecting said first and second spaces, said control means including means for discharging said spaces when the movable contact is in the closed position and pressurizing said spaces when the movable contact (2) leaves the sealing piston (3) during opening of the circuit breaker.
 5. Gas blast circuit breaker according to claim 1, in which the blast valve moving means includes an operating space (11) for the movable valve member (6) of the external blast valve, and the control means includes valve means (16) operatively connected to the push-rod means to discharge said operating space.
 6. Gas blast circuit breaker according to claim 5, including an inlet valve (14) for said operating space (11) for admitting pressure gas thereinto, said push-rod means including means to open said inlet valve when the movable contact moves away from closed position.
 7. Gas blast circuit breaker according to claim 6, in which the inlet valve (14) has a stem substantially perpendicular to the push-rod means (17), and a conical surface (23) on the push-rod means engageable with the end of said stem.
 8. Gas blast circuit breaker according to claim 6, in which the inlet valve (14) is positioned in line with the discharge valve (16). 